Each eyeglass lens typically has a peripheral beveled edge which seats in a corresponding groove in the eyeglass frame. Typically, the frame is sized to fit the wearer and the lenses must therefore be appropriately sized to fit the frame. Customarily, a right lens and a left lens are required, with the lenses not normally being interchangable. It has been common practice for the optician to stock a supply of lens blanks for the frames, the blanks having the required optical properties and being capable of being cut to the proper size.
Conventional glass lenses are cut to size and beveled with a relatively slowly rotating diamond wheel. Plastic lenses have increased in popularity more recently and conventional diamond grinding techniques are too slow. Router techniques have been used with plastic lenses in view of the highspeed cutting available but pattern warpage has been a problem.
The number and styles of eyeglass frames has increased tremendously and each style typically requires a special lens configuration. It is impractical for the optician to stock a supply of sized blanks for each style of frame, particularly when the necessary optical properties are considered. Furthermore, because of the numerous frame styles, the optician must be able to rapidly shift his shaper and edger from one frame style to another. Typically, each framemaker provides the optician with a pattern or patterns which are used to cut the lenses to fit the frame. Generally, there is one pattern per frame style so the edger and shaper must be able to appropriately cut the lens to the proper size for the given frame.
The high speed rotary cutters used in conventional router techniques generate much dust which must be evacuated to prevent damage to the machine. Furthermore, because of the high speeds employed, it is important that the edger and shaper have appropriate safety devices to prevent the operator from being injured. Conventional diamond grinding machines, on the other hand, generate large quantities of wet waste.
The disclosed invention is a plastic lens shaper and finisher employing router techniques in a manner which permits high speed cutting and finishing of the lenses in a safe way while successfully avoiding the problem of pattern warpage. The invention furthermore can be equipped with digital control systems to eliminate the need for individual physical patterns. The invention utilizes relatively low pressure pneumatic drive systems to control the movement between the shaping and finishing operations so that speed is maximized while pressure on the blank being cut is minimized. Lastly, the disclosed invention is particularly suited for an environment wherein long production runs are not possible and rapid interchangability from one frame style to another is required.